/*
 * libdivecomputer
 *
 * Copyright (C) 2018 Jef Driesen
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
 * MA 02110-1301 USA
 */

#include <string.h> // memcpy, memcmp
#include <stdlib.h> // malloc, free
#include <assert.h> // assert

#include "cressi_goa.h"
#include "context-private.h"
#include "device-private.h"
#include "checksum.h"
#include "array.h"
#include "platform.h"

#define ISINSTANCE(device) dc_device_isinstance((device), &cressi_goa_device_vtable)

#define CMD_VERSION 0x00
#define CMD_LOGBOOK 0x21
#define CMD_DIVE    0x22

#define HEADER  0xAA
#define TRAILER 0x55
#define END     0x04
#define ACK     0x06

#define SZ_DATA   512
#define SZ_PACKET 10
#define SZ_HEADER 23

#define FP_OFFSET 0x11
#define FP_SIZE   6

#define NSTEPS    1000
#define STEP(i,n) (NSTEPS * (i) / (n))

typedef struct cressi_goa_device_t {
	dc_device_t base;
	dc_iostream_t *iostream;
	unsigned char fingerprint[FP_SIZE];
} cressi_goa_device_t;

static dc_status_t cressi_goa_device_set_fingerprint (dc_device_t *abstract, const unsigned char data[], unsigned int size);
static dc_status_t cressi_goa_device_foreach (dc_device_t *abstract, dc_dive_callback_t callback, void *userdata);

static const dc_device_vtable_t cressi_goa_device_vtable = {
	sizeof(cressi_goa_device_t),
	DC_FAMILY_CRESSI_GOA,
	cressi_goa_device_set_fingerprint, /* set_fingerprint */
	NULL, /* read */
	NULL, /* write */
	NULL, /* dump */
	cressi_goa_device_foreach, /* foreach */
	NULL, /* timesync */
	NULL /* close */
};

static dc_status_t
cressi_goa_device_send (cressi_goa_device_t *device, unsigned char cmd, const unsigned char data[], unsigned int size)
{
	dc_status_t status = DC_STATUS_SUCCESS;
	dc_device_t *abstract = (dc_device_t *) device;

	if (size > SZ_PACKET) {
		ERROR (abstract->context, "Unexpected payload size (%u).", size);
		return DC_STATUS_INVALIDARGS;
	}

	// Setup the data packet.
	unsigned short crc = 0;
	unsigned char packet[SZ_PACKET + 8] = {
		HEADER, HEADER, HEADER,
		size,
		cmd
	};
	if (size) {
		memcpy (packet + 5, data, size);
	}
	crc = checksum_crc16_ccitt (packet + 3, size + 2, 0x000, 0x0000);
	packet[5 + size + 0] = (crc     ) & 0xFF; // Low
	packet[5 + size + 1] = (crc >> 8) & 0xFF; // High
	packet[5 + size + 2] = TRAILER;

	// Wait a small amount of time before sending the command. Without
	// this delay, the transfer will fail most of the time.
	dc_iostream_sleep (device->iostream, 100);

	// Send the command to the device.
	status = dc_iostream_write (device->iostream, packet, size + 8, NULL);
	if (status != DC_STATUS_SUCCESS) {
		ERROR (abstract->context, "Failed to send the command.");
		return status;
	}

	return status;
}

static dc_status_t
cressi_goa_device_receive (cressi_goa_device_t *device, unsigned char data[], unsigned int size)
{
	dc_status_t status = DC_STATUS_SUCCESS;
	dc_device_t *abstract = (dc_device_t *) device;

	unsigned char packet[SZ_PACKET + 8];

	// Read the header of the data packet.
	status = dc_iostream_read (device->iostream, packet, 4, NULL);
	if (status != DC_STATUS_SUCCESS) {
		ERROR (abstract->context, "Failed to receive the answer.");
		return status;
	}

	// Verify the header of the packet.
	if (packet[0] != HEADER || packet[1] != HEADER || packet[2] != HEADER) {
		ERROR (abstract->context, "Unexpected answer header byte.");
		return DC_STATUS_PROTOCOL;
	}

	// Get the payload length.
	unsigned int length = packet[3];
	if (length > SZ_PACKET) {
		ERROR (abstract->context, "Unexpected payload size (%u).", length);
		return DC_STATUS_PROTOCOL;
	}

	// Read the remainder of the data packet.
	status = dc_iostream_read (device->iostream, packet + 4, length + 4, NULL);
	if (status != DC_STATUS_SUCCESS) {
		ERROR (abstract->context, "Failed to receive the answer.");
		return status;
	}

	// Verify the trailer of the packet.
	if (packet[length + 7] != TRAILER) {
		ERROR (abstract->context, "Unexpected answer trailer byte.");
		return DC_STATUS_PROTOCOL;
	}

	// Verify the checksum of the packet.
	unsigned short crc = array_uint16_le (packet + length + 5);
	unsigned short ccrc = checksum_crc16_ccitt (packet + 3, length + 2, 0x0000, 0x0000);
	if (crc != ccrc) {
		ERROR (abstract->context, "Unexpected answer checksum.");
		return DC_STATUS_PROTOCOL;
	}

	// Verify the payload length.
	if (length != size) {
		ERROR (abstract->context, "Unexpected payload size (%u).", length);
		return DC_STATUS_PROTOCOL;
	}

	if (length) {
		memcpy (data, packet + 5, length);
	}

	return status;
}

static dc_status_t
cressi_goa_device_download (cressi_goa_device_t *device, dc_buffer_t *buffer, dc_event_progress_t *progress)
{
	dc_status_t status = DC_STATUS_SUCCESS;
	dc_device_t *abstract = (dc_device_t *) device;

	const unsigned char ack[] = {ACK};
	const unsigned int initial = progress ? progress->current : 0;

	// Erase the contents of the buffer.
	if (!dc_buffer_clear (buffer)) {
		ERROR (abstract->context, "Insufficient buffer space available.");
		return DC_STATUS_NOMEMORY;
	}

	unsigned int skip = 2;
	unsigned int size = 2;
	unsigned int nbytes = 0;
	while (nbytes < size) {
		// Read the data packet.
		unsigned char packet[3 + SZ_DATA + 2];
		status = dc_iostream_read (device->iostream, packet, sizeof(packet), NULL);
		if (status != DC_STATUS_SUCCESS) {
			ERROR (abstract->context, "Failed to receive the answer.");
			return status;
		}

		// Verify the checksum of the packet.
		unsigned short crc = array_uint16_le (packet + sizeof(packet) - 2);
		unsigned short ccrc = checksum_crc16_ccitt (packet + 3, sizeof(packet) - 5, 0x0000, 0x0000);
		if (crc != ccrc) {
			ERROR (abstract->context, "Unexpected answer checksum.");
			return DC_STATUS_PROTOCOL;
		}

		// Send the ack byte to the device.
		status = dc_iostream_write (device->iostream, ack, sizeof(ack), NULL);
		if (status != DC_STATUS_SUCCESS) {
			ERROR (abstract->context, "Failed to send the ack byte.");
			return status;
		}

		// Get the total size from the first data packet.
		if (nbytes == 0) {
			size += array_uint16_le (packet + 3);
		}

		// Calculate the payload size of the packet.
		unsigned int length = size - nbytes;
		if (length > SZ_DATA) {
			length = SZ_DATA;
		}

		// Append the payload to the output buffer.
		if (!dc_buffer_append (buffer, packet + 3 + skip, length - skip)) {
			ERROR (abstract->context, "Insufficient buffer space available.");
			return DC_STATUS_NOMEMORY;
		}

		nbytes += length;
		skip = 0;

		// Update and emit a progress event.
		if (progress) {
			progress->current = initial + STEP(nbytes, size);
			device_event_emit (abstract, DC_EVENT_PROGRESS, progress);
		}
	}

	// Read the end byte.
	unsigned char end = 0;
	status = dc_iostream_read (device->iostream, &end, 1, NULL);
	if (status != DC_STATUS_SUCCESS) {
		ERROR (abstract->context, "Failed to receive the end byte.");
		return status;
	}

	// Verify the end byte.
	if (end != END) {
		ERROR (abstract->context, "Unexpected end byte (%02x).", end);
		return DC_STATUS_PROTOCOL;
	}

	// Send the ack byte to the device.
	status = dc_iostream_write (device->iostream, ack, sizeof(ack), NULL);
	if (status != DC_STATUS_SUCCESS) {
		ERROR (abstract->context, "Failed to send the ack byte.");
		return status;
	}

	return status;
}

static dc_status_t
cressi_goa_device_transfer (cressi_goa_device_t *device,
                            unsigned char cmd,
                            const unsigned char input[], unsigned int isize,
                            unsigned char output[], unsigned int osize,
                            dc_buffer_t *buffer,
                            dc_event_progress_t *progress)
{
	dc_status_t status = DC_STATUS_SUCCESS;

	// Send the command to the dive computer.
	status = cressi_goa_device_send (device, cmd, input, isize);
	if (status != DC_STATUS_SUCCESS) {
		return status;
	}

	// Receive the answer from the dive computer.
	status = cressi_goa_device_receive (device, output, osize);
	if (status != DC_STATUS_SUCCESS) {
		return status;
	}

	// Download the optional and variable sized payload.
	if (buffer) {
		status = cressi_goa_device_download (device, buffer, progress);
		if (status != DC_STATUS_SUCCESS) {
			return status;
		}
	}

	return status;
}


dc_status_t
cressi_goa_device_open (dc_device_t **out, dc_context_t *context, dc_iostream_t *iostream)
{
	dc_status_t status = DC_STATUS_SUCCESS;
	cressi_goa_device_t *device = NULL;

	if (out == NULL)
		return DC_STATUS_INVALIDARGS;

	// Allocate memory.
	device = (cressi_goa_device_t *) dc_device_allocate (context, &cressi_goa_device_vtable);
	if (device == NULL) {
		ERROR (context, "Failed to allocate memory.");
		return DC_STATUS_NOMEMORY;
	}

	// Set the default values.
	device->iostream = iostream;
	memset (device->fingerprint, 0, sizeof (device->fingerprint));

	// Set the serial communication protocol (115200 8N1).
	status = dc_iostream_configure (device->iostream, 115200, 8, DC_PARITY_NONE, DC_STOPBITS_ONE, DC_FLOWCONTROL_NONE);
	if (status != DC_STATUS_SUCCESS) {
		ERROR (context, "Failed to set the terminal attributes.");
		goto error_free;
	}

	// Set the timeout for receiving data (3000 ms).
	status = dc_iostream_set_timeout (device->iostream, 3000);
	if (status != DC_STATUS_SUCCESS) {
		ERROR (context, "Failed to set the timeout.");
		goto error_free;
	}

	// Clear the RTS line.
	status = dc_iostream_set_rts (device->iostream, 0);
	if (status != DC_STATUS_SUCCESS) {
		ERROR (context, "Failed to clear the RTS line.");
		goto error_free;
	}

	// Clear the DTR line.
	status = dc_iostream_set_dtr (device->iostream, 0);
	if (status != DC_STATUS_SUCCESS) {
		ERROR (context, "Failed to clear the DTR line.");
		goto error_free;
	}

	dc_iostream_sleep (device->iostream, 100);
	dc_iostream_purge (device->iostream, DC_DIRECTION_ALL);

	*out = (dc_device_t *) device;

	return DC_STATUS_SUCCESS;

error_free:
	dc_device_deallocate ((dc_device_t *) device);
	return status;
}

static dc_status_t
cressi_goa_device_set_fingerprint (dc_device_t *abstract, const unsigned char data[], unsigned int size)
{
	cressi_goa_device_t *device = (cressi_goa_device_t *) abstract;

	if (size && size != sizeof (device->fingerprint))
		return DC_STATUS_INVALIDARGS;

	if (size)
		memcpy (device->fingerprint, data, sizeof (device->fingerprint));
	else
		memset (device->fingerprint, 0, sizeof (device->fingerprint));

	return DC_STATUS_SUCCESS;
}

static dc_status_t
cressi_goa_device_foreach (dc_device_t *abstract, dc_dive_callback_t callback, void *userdata)
{
	dc_status_t status = DC_STATUS_SUCCESS;
	cressi_goa_device_t *device = (cressi_goa_device_t *) abstract;
	dc_buffer_t *logbook = NULL;
	dc_buffer_t *dive = NULL;

	// Enable progress notifications.
	dc_event_progress_t progress = EVENT_PROGRESS_INITIALIZER;
	device_event_emit (abstract, DC_EVENT_PROGRESS, &progress);

	// Read the version information.
	unsigned char id[9] = {0};
	status = cressi_goa_device_transfer (device, CMD_VERSION, NULL, 0, id, sizeof(id), NULL, NULL);
	if (status != DC_STATUS_SUCCESS) {
		ERROR (abstract->context, "Failed to read the version information.");
		goto error_exit;
	}

	// Emit a vendor event.
	dc_event_vendor_t vendor;
	vendor.data = id;
	vendor.size = sizeof (id);
	device_event_emit (abstract, DC_EVENT_VENDOR, &vendor);

	// Emit a device info event.
	dc_event_devinfo_t devinfo;
	devinfo.model = id[4];
	devinfo.firmware = array_uint16_le (id + 5);
	devinfo.serial = array_uint32_le (id + 0);
	device_event_emit (abstract, DC_EVENT_DEVINFO, &devinfo);

	// Allocate memory for the logbook data.
	logbook = dc_buffer_new(4096);
	if (logbook == NULL) {
		ERROR (abstract->context, "Failed to allocate memory.");
		goto error_exit;
	}

	// Read the logbook data.
	status = cressi_goa_device_transfer (device, CMD_LOGBOOK, NULL, 0, NULL, 0, logbook, &progress);
	if (status != DC_STATUS_SUCCESS) {
		ERROR (abstract->context, "Failed to read the logbook data.");
		goto error_free_logbook;
	}

	const unsigned char *logbook_data = dc_buffer_get_data(logbook);
	size_t logbook_size = dc_buffer_get_size(logbook);

	// Count the number of dives.
	unsigned int count = 0;
	unsigned int offset = logbook_size;
	while (offset > SZ_HEADER) {
		// Move to the start of the logbook entry.
		offset -= SZ_HEADER;

		// Get the dive number.
		unsigned int number= array_uint16_le (logbook_data + offset);
		if (number == 0)
			break;

		// Compare the fingerprint to identify previously downloaded entries.
		if (memcmp (logbook_data + offset + FP_OFFSET, device->fingerprint, sizeof(device->fingerprint)) == 0) {
			break;
		}

		count++;
	}

	// Update and emit a progress event.
	progress.maximum = (count + 1) * NSTEPS;
	device_event_emit (abstract, DC_EVENT_PROGRESS, &progress);

	// Allocate memory for the dive data.
	dive = dc_buffer_new(4096);
	if (dive == NULL) {
		ERROR (abstract->context, "Failed to allocate memory.");
		goto error_free_logbook;
	}

	// Download the dives.
	offset = logbook_size;
	for (unsigned int i = 0; i < count; ++i) {
		// Move to the start of the logbook entry.
		offset -= SZ_HEADER;

		// Read the dive data.
		status = cressi_goa_device_transfer (device, CMD_DIVE, logbook_data + offset, 2, NULL, 0, dive, &progress);
		if (status != DC_STATUS_SUCCESS) {
			ERROR (abstract->context, "Failed to read the dive data.");
			goto error_free_dive;
		}

		const unsigned char *dive_data = dc_buffer_get_data (dive);
		size_t dive_size = dc_buffer_get_size (dive);

		// Verify the header in the logbook and dive data are identical.
		// After the 2 byte dive number, the logbook header has 5 bytes
		// extra, which are not present in the dive header.
		if (dive_size < SZ_HEADER - 5 ||
			memcmp (dive_data + 0, logbook_data + offset + 0, 2) != 0 ||
			memcmp (dive_data + 2, logbook_data + offset + 7, SZ_HEADER - 7) != 0) {
			ERROR (abstract->context, "Unexpected dive header.");
			status = DC_STATUS_DATAFORMAT;
			goto error_free_dive;
		}

		// Those 5 extra bytes contain the dive mode, which is required for
		// parsing the dive data. Therefore, insert all 5 bytes again. The
		// remaining 4 bytes appear to be some 32 bit address.
		if (!dc_buffer_insert (dive, 2, logbook_data + offset + 2, 5)) {
			ERROR (abstract->context, "Out of memory.");
			status = DC_STATUS_NOMEMORY;
			goto error_free_dive;
		}

		dive_data = dc_buffer_get_data (dive);
		dive_size = dc_buffer_get_size (dive);

		if (callback && !callback(dive_data, dive_size, dive_data + FP_OFFSET, sizeof(device->fingerprint), userdata))
			break;
	}

error_free_dive:
	dc_buffer_free(dive);
error_free_logbook:
	dc_buffer_free(logbook);
error_exit:
	return status;
}